We decided to arbitrary define the depth of function return trace as "20".Perhaps this is not enough. To help finding an optimal depth, we measure nowthe overrun: the number of functions that have been missed for the current thread.By default this is not displayed, we have to do set a particular flag on the returntracer: echo overrun > /debug/tracing/trace_optionsAnd the overrun will be printed on the right.As the trace shows below, the current 20 depth is not enough.